<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <style>
        div{
            width:200px;
            height:200px;
            background-color: aqua;
            /*边框类型*/
            border-style: dashed;
            /*边框颜色*/
            border-color:red;
            /*边框宽度*/
            border-width:5px;

        }
    </style>
</head>
<body>
<div>你好</div>
</body>
</html>